plantparasitic

Plant-parasitic organisms are those that obtain nutrients from living plants to the detriment of the host. The category includes several groups, notably plant-parasitic nematodes, parasitic plants, and various pathogens such as fungi, bacteria, and viruses. These organisms differ in biology and pathogenicity but share the common goal of exploiting plant tissues for food and growth, often causing reduced vigor, wilting, necrosis, or yield losses.

Plant-parasitic nematodes are microscopic roundworms that invade roots, stems, or leaves. They use specialized mouthparts to pierce plant cells and may form feeding sites that divert nutrients. Root-knot nematodes (Meloidogyne) induce galls on roots, while cyst nematodes (Heterodera, Globodera) form protective cysts. Other nematodes cause root lesions or stem infections. Nematode damage is commonly associated with stunting, chlorosis, and poor water uptake, and their management is a major concern in agriculture.

Parasitic plants such as Cuscuta (dodder), Striga, and Orobanche attach to host tissues with specialized structures called haustoria that connect to the host's vascular system and siphon off water and nutrients. Some are facultative, others obligate, and they can affect crops and wild plants, often in nutrient-poor environments or disturbed ecosystems.

Fungal pathogens include rusts, mildews, blights, and rot-causing species that form haustoria or penetrate host tissues. Bacterial pathogens, including Xanthomonas and Pseudomonas species, invade through natural openings or wounds, causing softening and rot. Plant viruses, transmitted by vectors or mechanical means, cause mosaics, rings, and growth defects. Together with nematodes and parasitic plants, these agents contribute to substantial agricultural losses worldwide.

Detection relies on symptom observation, microscopy, and molecular methods; management emphasizes surveillance, resistant cultivars, crop rotation, sanitation, soil amendments, and, where appropriate, biological controls or targeted chemicals. Integrated pest management aims to minimize crop damage while reducing non-target effects.